The present invention relates to a mechanical lumbar support for a seat back. More specifically, the present invention relates to a mechanical lumbar support intended for use in an automotive seat.
Consumer trends have forced automobile manufacturers to provide ever increasing levels of comfort in the products being offered for sale. This includes providing multiple seat adjustment components such as reclining mechanisms, headrest height and tilt adjusters, and variable lumbar support devices. These components are designed to meet the physical needs of various sizes of seat occupants. However, to meet these needs, these comfort components require a high level of complexity due to the number of moving parts necessary to provide support at various locations. In particular, the variable lumbar support devices presently being used have included cables and pulley devices that are threaded throughout the seat back.
The complexity of lumbar support devices of the present art consume a significant amount of packaging space and add a considerable amount of mass to the seat. One such device is disclosed in U.S. Pat. No. 5,567,011 to Sessini. Sessini discloses a lumbar support device that requires a cord be threaded through a seat back and routed with a series of pulleys for both adjusting the height and the magnitude of the lumbar support. While devices such as this fulfill comfort expectations, they are costly to produce and difficult to assemble. Further, this type of device requires that a seat back have considerable thickness to enclose all of the lumbar adjustment components.
Therefore, it would be desirable to design an adjustable lumbar support device that meets the needs of various sizes of seat occupants and yet does not adversely affect mass, cost, or packaging space of the vehicle.
This invention relates to a powered lumbar support device intended for use in an automobile seat back. The device includes a resilient panel that has an upper flange and a lower flange and is biased in a forward direction for providing an arch in the seat back. A lumbar frame secures the support device to the seat back. A control module affixed to the lumbar frame. An extending member projects from the control module and affixes to the upper flange. The control module includes a drive mechanism capable of changing the distance between the upper flange and the lower flange by extending and retracting the extending member. By changing the distance between the first flange and the second flange, the arch in the resilient sheet can be changed for adjusting the amount of lumbar support. The control module is secured by a compliant spring to the lumbar frame, but otherwise is slidable on the lumbar frame in a vertical direction.
The compliant spring includes a contracting spring force that is greater than the extending force generated by the drive mechanism. Therefore, the compliant spring will prevent the control module from sliding upon the lumbar frame. However, when the resilient panel is subjected to enough force to overcome the contracting spring force, the compliant spring stretches increasing the distance between the first flange and the second flange changing the arch in the resilient panel. The compliance provided to the resilient panel by the resilient spring provides an additional level of comfort to the seat occupant not otherwise available in a rigid lumbar support device.
The control module is powered by a small electric motor eliminating the need for cable and pulley devices for changing the amount and the location of the lumbar support in the seat back. Further, the control device is packaged into a compact lumbar support module that is easily installed into a seat back frame without having to route cables. Due to the compact nature of the control module, lumbar support can be provided in seat backs that are much thinner than those currently in use. Still further, the modules are much less expensive to produce than the current cable and pulley style devices. The low cost provides the ability to install lumbar support devices into economically priced automobiles.